title: Unique and selective expression of L-amino acid transporter 1 in human tissue as well as being an aspect of oncofetal protein.
abstract: Dysregulated expression of L-type amino acid transporter 1 (LAT1), which transports large neutral amino acids, is a characteristic of various human cancers and possibly offers a molecular target for chemotherapy. LAT2, in contrast, shows lower expression in neoplasms. LAT1 is presumed to be a biomarker of many cancers, suggesting a kind of oncoprotein. However, no precise analysis of LAT1 and LAT2 expression has been performed in systemic normal tissues. To see characteristics of LAT1 and LAT2, immunohistochemical expression of LAT1 and LAT2 was assessed and compared in normal human systemic organs and tissues from 3 adults, 3 children and 3 fetuses in the present study. Cardiac muscles, hepatocytes, thymic epithelial cells and primitive neuroectodermal cells in fetus were positive with LAT1, whereas no expression was found in the respective adult tissues, indicating an aspect of oncofetal protein. In adult tissues, LAT1 was found to be expressed proximal to proliferative zones in gastrointestinal mucosa by double immunostaining of LAT1 and Ki-67. Testicular Sertoli cells, ovarian follicular cells, and pancreatic islet cells showed strong expression. Although the systemic capillary endothelium did not express LAT1, but did express LAT2, capillaries corresponding to the blood-brain, blood-follicle, and blood-retinal barriers demonstrated strong LAT1 immunoreactions. In conclusion, LAT1 was expressed in gonad tissues and several kinds of cells having special functions, as well as being discovered to be an aspect of oncofetal protein. In addition, ubiquitous LAT2 expression was confirmed immunohistochemically in systemic tissues, indicating constitutional function.
authors.affiliation: Department of Pathology, and Department of Cellular and Histopathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan. dm09021q@st.kitasato-u.ac.jp.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Nakada
authors.affiliation: Department of Pathology, and Department of Cellular and Histopathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Tetuo
authors.initials: T
authors.lastname: Mikami
authors.affiliation: J-Pharma Co., Ltd., Shinjuku, Tokyo, Japan.
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Hana
authors.affiliation: Department of Pathology, and Department of Cellular and Histopathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ichinoe
authors.affiliation: Department of Pathology, and Department of Cellular and Histopathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yanagisawa
authors.affiliation: Department of Pathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: J-Pharma Co., Ltd., Shinjuku, and Department of Pharmacology and Toxicology, Kyorin University, School of Medicine, Mitaka, Tokyo, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endou
authors.affiliation: Department of Pathology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Okayasu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000293:Adolescent; D000367:Age Factors; D000368:Aged; D005260:Female; D005333:Fetus / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000378:metabolism; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007668:Kidney / Q000378:metabolism; D027283:Large Neutral Amino Acid-Transporter 1 / Q000378:metabolism*; D008297:Male; D010053:Ovary / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C419196:LAT2 protein, human; D027283:Large Neutral Amino Acid-Transporter 1